Glyphosate is a broad-spectrum herbicide useful in both non-selective and, with the advent of glyphosate tolerant crops, selective weed control. It is generally non-selective and is very effective on deep-rooted perennial species and on annual and biennial species of grasses, sedges and broadleaf weeds. By modifying the genetic make-up of some plant species, various crops can now be grown with resistance to glyphosate herbicidal activity. It is critical that new formulations of glyphosate do not injure these genetically modified plants.
Glyphosate preferably refers to the following compounds: 
And derivatives thereof.
The solubility of glyphosate acid is relatively low in water (about 1 to about 2%). Since glyphosate is an acid, however, numerous water-soluble salts can be formed. In U.S. Pat. Nos. 4,405,531 and 3,799,758, Franz discusses numerous glyphosate derivatives and homologues, including halogen, hydroxy, thio, ammonium, mono- and di-alkylamine, hydroxy-alkyl and alkenyl amine, hydrocarbyl, hydrocarbonoxyhydrocarbyl, halohydrocarbyl, and halo-hydrocarbonoxyhydrocarbyl, esters and tioesters, aminohydrocarbyl, metallo-oxy including alkali and alkaline earth, copper, zinc, manganese and nickel-oxy, aminoxy, organic aminoxy, and/or strong acid salt derivatives and homologues. According to Franz, the alkali, alkaline earth, ammonium and organic amine salts are preferred.
Ammonia, potassium, isopropylamine, and sesquisodium salts of glyphosate have been used in the past to enhance water solubility. Isopropylamine is the most common of these amine salts. Monsanto Chemical Company""s Trademarked ROUNDUP(copyright) Herbicide is an example of an Isopropylamine salt of glyphosate. Monsanto Chemical Company""s Trademarked ROUNDUP(copyright) DRY PAK is an example of a dry ammonium salt of glyphosate. Zeneca Ag Products"" Trademarked TOUCHDOWN(copyright) is an example of a diammonium salt of glyphosate.
Numerous patents have been granted to protect formulations of glyphosate and it""s salts. Generally, these formulations offer more effective applications of the herbicide. A few examples of patented glyphosate formulations are discussed here. In U.S. Pat. No. 5,668,085, Forbes et al., describes formulations of glyphosate containing alkoxylated amine surfactants. In U.S. Pat. No. 5,710,104, Magin et al., describes glyphosate compositions containing polyethoxylated monohydric primary alcohol. In U.S. Pat. No. 5,464,807, Claude et al., describes unique formulations of glyphosate and alkoxylated quaternary ammonium surfactants. U.S. Pat. No. 5,118,338 describes a formulation containing glyphosate acid and dry surfactant. This final formulation is a dry product.
In U.S. Pat. No. 5,302,579, Young describes a glyphosate acid formulation containing sulfuric acid and optionally a chalcogen compound. Young further instructs that hydrochloric acid does not form soluble reaction products with glyphosate. Sulfuric acid and hydrochloric acid can bring undesirable effects on plant tissue. In U.S. Pat. No. 5,034,046, Young actually discloses the use of a formulation of sulfuric acid and urea to control vegetation. With the use of glyphosate over the top of genetically modified crops, phytotoxicity is not acceptable.
Darchy et al., teaches in U.S. Pat. No. 5,180,414 the use of a glyphosate formulation containing phosphate ester surfactants of the formula: 
Wherein R is an alkl radical having 4 to 12 carbon atoms, n is an integer from 2 to 10 and M is hydrogen, sodium, ammonium or alkylammonium.
Darchy at col. 3 warns against formulations with too much acidity and reports that they may precipitate the glyphosate.
Sato et al., teaches in U.S. Pat. No. 6,083,875 the use of phosphated solvents having a water solubility of less than 1%. His preferred embodiments are triaryl phosphates and formulations minimize the level of these phosphated solvents.
Frisch et al., teaches in U.S. Pat. No. 4,853,026 the use of ethoxylated acidic phosphoric acid esters. These formulations contain at least 2 herbicides and use phosphate esters as surfactants/emulsifiers.
Horibe et al., teaches in WO018236A1, WO9819544A1 and U.S. Pat. No. 6,200,929 the use of phosphorous acid derivatives in combination with glyphosate. The phosphorous acid derivative is of the following structure: 
wherein R1 represents a C1-8 alkyl group (said alkyl group may be substituted with 1 to 3 halogen atoms or 1 to 3, C1-3 alkoxy groups), a phenyl group or a benzyl group; M represents a hydrogen atom, an ammonium group (said ammonium group may be substituted with 1 to 4 C1-3 alkyl groups), a sodium atom, a potassium atom, a lithium atom, a magnesium atom, a calcium atom, a barium atom, a zinc atom, a manganese atom, a copper atom, an iron atom, a nickel atom or an aluminum atom; and m stands for an integer equivalent to the positive valency of M. R1 is not taught to be only H. The phosphorous acid must be a derivative and not phosphorous acid alone.
Maier teaches in WO9927781A1 the use of phosphate esters in combination with other surfactants for use in glyphosate formulations.
We have surprisingly discovered that phosphoric and phosphorous acids can be used to dissolve Glyphosate acid. These acid-solubolized formulations have further been discovered to dramatically improve the herbicidal effectiveness of glyphosate. Furthermore, we have discovered that salts of these acids and organic carboxylic acids can be used to dissolve glyphosate.
The invention relates to a herbicidal composition comprising
(a) Glyphosate in the free acid form,
(b) at least one acid component selected from the group consisting of
(1) phosphoric acid,
(2) phosphorous acid (H3PO3),
(3) a neutralized organic acid,
(4) salts of phosphoric acid and
(5) salts of phosphorous acid and optionally (c) a surfactant.
The invention relates to a herbicidal composition comprising
(a) glyphosate in the free acid form,
(b) at least one acid component selected from the group consisting of
a. phosphoric acid,
b. phosphorous acid (H3PO3),
c. a neutralized organic acid,
d. salts of phosphoric acid and
e. salts of phosphorous acid and optionally (c) a surfactant.
The water solubility of Glyphosate is approximately 1.2%. Using phosphoric, acetic, citric, propionic, and phosphorous acids, glyphosate can be solubolized at as much as about 20 to about 30% in the acid. The formulation will contain from about 1 to about 30% of glyphosate acid. The preferred embodiment of this formulation will contain about 5 to about 25% glyphosate acid. The most preferred embodiment of this formulation contains about 5 to about 20% glyphosate acid.
Phosphoric acid and phosphorous acid are significantly different than the phosphoric acid esters (also known as phosphate esters) and the phosphorous acid derivatives discussed in the prior art. In the context of this invention, the phosphate esters are surfactants and not an acid component. Phosphoric acid esters are surfactants that are well known for their emulsifying ability in high electrolyte solutions such as fertilizers. Optionally, the acids can be neutralized to form stable formulations.
The formulation will contain about 1 to about 99% of phosphoric acid (H3PO4), acetic acid, citric acid, propionic acid, or phosphorous acid (H3PO3). Combinations of these acids can also be used. The preferred embodiment of this formulation will contain about 40 to about 99%, preferably about 50 to about 99% of phosphoric, phosphorous, citric, propionic or acetic acid. The most preferred embodiment will contain about 80 to about 90% of phosphoric, phosphorous, citric, propionic, or acetic acid.
The phosphoric acid or phosphorous acids can be neutralized without losing solubility of the glyphosate acid. Preferably, the acid will be neutralized with ammonia (NH3), Potassium (K) or Sodium (Na). Most preferably, the phosphoric, phosphorous, citric, propionic or acetic acids can be neutralized with potassium or ammonia.
Preferably the organic acid is neutralized to make either an ammonia or potassium salt of the organic acid and preferably said herbicidal composition has a pH or less than about 6.0, more preferably a pH of less than 5.0, more preferably a pH of less than 4.0 and most preferably a pH of less than 4.0.
The salts of phosphoric acid and the salts of phosphorous acid are preferably ammonia or potassium salts of phosphoric acid or phosphorous acid and said herbicidal composition has a pH or less than about 6.0 more preferably a pH of less than 5.0, more preferably a pH of less than 4.0 and most preferably a pH of less than 4.0.
The formulation can be further enhanced with the addition of a surfactant component. The surfactant can be any known to reduce the surface tension of water by at least 5 dynes/cm. The surfactant can be present at 1% w/w in water, reduces the surface tension of water to less than 60 dynes.
Useful surfactants include but are not limited to:
Alcohol alkoxylates including but not limited to:
Based on branched and linear alcohols
Those containing ethylene oxide or propylene oxide
Alcohol alkoxylate sulfates,
Alkylphenol alkoxylates including but not limited to:
Nonylphenol and octylphenols.
Those containing ethylene oxide or propylene oxide
Alkanolamides,
Alkylaryl sulfonates,
Amine oxides
Amines including but not limited to:
Fatty amine alkoxylates such as but not limited to tallowamine alkoxylates,
Betaine derivatives,
Block polymers of ethylene and propylene glycol,
Carboxylated alcohol or alkylphenol alkoxylates,
Diols, including but not limited to Butanediols,
Diphenyl sulfonate derivatives,
Ethers, including but not limited to
Butyl celluslove,
Butyl carbitol,
Ethoxylated amines,
Ethoxylated fatty acids,
Ethoxylated fatty esters and oils,
Ethylene carbonate,
Fatty esters,
Glycerol esters,
Glycols including but not limited to
Propylene glycol,
Ethylene glycol,
Dipropylene glycol,
Diethylene glycol,
Phosphate ester surfactants including but not limited to
Phosphate esters of alcohol alkoxylates,
Phosphate esters of alkylphenol alkoxylates,
Propylene Carbonate,
Sarcosine derivatives,
Silicone-based surfactants,
Sorbitan derivatives including but not limited to:
Sorbitan esters,
Alkoxylated sorbitan esters,
Sucrose and glucose derivatives including but not limited to:
Alkylpolyglucosides,
Sulfates and sulfonates of alkoxylated alkylphenols,
Sulfates of alcohols,
Tristyrylphenol Alkoxylates,
Other surfactants are disclosed in McCutcheon""s Emulsifiers and Detergents, North American Edition, 2000.
Other surfactants are disclosed in the following patents:
U.S. Pat. No. 5,741,502 Homogeneous, essentially nonaqueous adjuvant compositions with buffering capability
U.S. Pat. No. 5,725,630 Dry granular fertilizer blend and a method of fertilizing plants
U.S. Pat. No. 5,580,567 Homogeneous, essentially nonaqueous adjuvant compositions with buffering capability
U.S. Pat. No. 5,393,791 Homogeneous, essentially nonaqueous adjuvant compositions with buffering capability
U.S. Pat. No. 5,234,919 Water soluble, highly active dimethoate formulations in an alcohol/ester solvent system
U.S. Pat. No. 5,178,795 Homogeneous, essentially nonaqueous adjuvant compositions with buffering capability
U.S. Pat. No. 5,906,961 Alkanolamide spreader-sticker surfactant combination
U.S. Pat. No. 5,877,112 Agricultural formulation
U.S. Pat. No. 6,232,272 Manufacture and use of herbicide chlorinated phenoxy formulation
All the references described herein are incorporated by reference in its entirety for all useful purposes.
The herbicidal composition can contain less than about 15% by weight water. The herbicidal composition preferably has a ratio of acid to glyphosate of at least about 2:1 and at most about 99:1.
The formulations described herein are intended for use in aqueous based systems. The pesticide applicator will generally dilute the herbicide formulation with water or aqueous fertilizers to apply to plants.